This invention is related to the method of making heat-resistant polyester in which the amount of end carboxyl group (hereinafter, this will be abbreviated by COOH) has been reduced.
As to the method of reducing the COOH of polyester, various methods have been proposed. As the typical example, the method of reacting the polyester and epoxy compound is known. However, the present inventors have examined this method and found that the addition of epoxy compounds reduces the COOH but it also reduces the degree of polymerization and that, depending on the epoxy compound, its reactivity with the COOH of polyester is not sufficient, giving insufficient effect.